Method of preventing corrosion by sulphur compounds during conversion of hydrocarbons



Aug. 23, 1932. A. P. sAcHs 1,873,851

METHOD OF PREVENTING CORROSION BY SULPHUR COMPOUNDS DURING CONVERSION OF HYDROCARBONS Filed June 2-4, 1929 R Y E mm N we m m A no 0 n 8% M A Y B corrosive petroleum vapors is a non-exclusive Patented Aug. 23, 1932 UNITED STATES PATENT OFFICE ALBERT P. SACHS, OF NEW YORK N. Y., ASSIGNOR TO PETROLEUM CONVERSION COB- IPORATION, OF NEW YORK, N. Y.,'

A CORPORATION OF NEW YORK METHOD OF PREVENTING CORROSION I BY SULIHUR COMPOUNDS DURING CONVERSION OF HYDROCABIBONS Application filed June 24,

particularly itrelates to the prevention of corrosion of the metal parts of the apparatus by the presence of sulphur. It is my observation that the corrosiveness of even the most function of the sulphur content andthat when the sulphur is reduced below a certain percentage substantially no corrosion is experienced. This critical value I have found in practice to be 1% although this may vary slightly for different operating conditions. In a previous application, Serial No. 310,892, filed October 6, 1928, I considered the problem of sulphur removal from the carrier gas prior to its admission to the heating element andpointed out the advantage of keeping the conditions under which the cracking reaction takes place non-oxidizing, in order that the sulphur compounds may not be converted into sulphur dioxide or sulphur trioxide, in which form they are much more highly corrosive. Accordingly, it will be understood that in carrying out the present invention the conditions in the reaction chamber will be maintained non-oxidizing, as by avoiding the use of steam or other agent having an oxidizing effect.

Based upon my discovery I so dilute such vapor with.carrier-gas so as to arrive at a mixture the sulphur content of which will be not greater than 1%. Since the temperature of the mixture is fixed by the conditions of operation it is therefore necessary to vary either the temperature of the vapor fed to the reaction chamber or that of the carrier gas so as to compensate for variation in the ratio of oil vapor to carrier gas While producing a final mixture of uniform temperature. In the embodiment shown and described, this adjustment of the temperature required is brought about by varying the temperature of theoil vapor.

My invention will be best understood with reference to the following description of the processto which it has been applied taken 1929. Serial No. 373,238.

with the annexed drawing which illustrates the apparatus in which the process may be carried out.

In said drawing, oil previously heated in the system is fed to tl 1e vaporizer 10, is led therefrom through a pipe 11 having a parallel connection with a superheater 12, the oil vapor being then admitted to a reaction chamber 13. At the same timeheat-carrier gas is admitted to a hot blast stove 15 or other type of regenerative heater through a pipe 16, the gas being heated in said stove and leaving same through a pipe 17 through which it is conducted to reaction chamber 13. The vapor of the oil admittedto the reaction chamber 13 is converted by means of the thus heated carrier-gas and the mixture is led therefrom through a pipe 20 to a scrubber 21 wherein the reaction products are contacted with a suitable menstruum, as for example a heavy oil. This action is effective' to remove the suspended carbon in said gas and vapor mixture and also to abstract a portion of the sensible heat therein. The now scrubbed gaseous products leave the scrubber 21 through a pipe 22 and are then admitted to a rectifying column 23 wherein the heavier fractions are dropped out by means of a suitable liquid oil admitted through pipe 24, such oil conveniently being the oil entering the system and which is then led from said column to the evaporator 10 as The carrierabsorber 30 wherein theverylight ends are I condensed out.

Returning to scrubber 21, the menstruum used therein leaves the apparatus through a pipe 35 through which it is passed to a heat exchanger 36 and thence to a second heat exchanger 37, through pipe 38, and thence through pipe 40 to a reservoir 41. From .said reservoir it is then pumped through pipe 42 back into scrubber 21.

The now stripped carrier-gas leaving the absorber 30 passes through a pipe 44, through heat exchanger 36 wherein it is heated by means of the hot menstruum' therein but out of direct contact therewith, and thence is passed through pipe 16 back to the stove 15. Or, if desired, all or a portion of said gas may be stored in the gas holder 45.

The oil entering the system through pipe 24 after passing through rectifier 23 wherein the light ends are removed, thence passes through heat exchanger 37 wherein its temperature is raised, and thence through pipe 46 to evaporator 10.

As previously indicated, the vapors leaving the evaporator 10 are desirably superheated in the superheater 12 without, however, producing substantial-cracking of such vapors. By means of the valves 48, 49 the amount of oil vapor so superheated may'be varied. In addition, means are provided for varying the temperature of the carrier-gas admitted to the reaction chamber 13, such means comprising a by-pass 50 joining the cold gas main 16 with the hot gas main 17 suitable valves 52, 53, 54 being provided to accomplish this distribution of the cold gas, the control of one of these valves, as for example valve 53 being accomplished preferably by automatic, thermostatically actuated means, not shown.

Having described the general process to which the invention is applicable, the following examples of runs using specific types of charge may be given as illustrative of myinvent-ion:

E wample I .Let it be assumed that an oil having less than the critical value of sulphur, i. e. 1%, is employed; obviously since the sulphur content of heat carrier gas is maintained at a low value, say around 0.1% (preferably in accordance with the method disclosed in applicantsco-pending application, Serial No. 310,892, filed October 6, 1928), the final mixture of oil vapor and heat carrier gas will be less than 1%, and the ratios of heat carrier gas and oil vapor may then assume any value as may be required by considerations of thermal efliciency as for example:

Charging stock:

f ordinary type containing less than 1% sulphur by weight.

Heat carrier gas:

Containing 0.1% sulphur by weight and having the following composition by volume:

Per cent by volume CH 60 H 35 CO and other constituents 5 Specific heat in B. t. 11. per cubic foot1.56. Temperature of oil vapor (specific heat= 0.5) admitted to reaction chamber-800 F.

Temperature of heat carrier gas admitted to reaction chamber1250 F.

Initial temperature of the mixture of heat carrier gas and oil vapor960 F.

Ratio of weight of oil vapor to weight of heat carrier gas equals 1:.176.

(160 .5=B. t. u. necessary to raise one pound of oil vapor from 800 to 960. 290 X 1.56=453 B. t. u. furnished by one pound of heat carrier gas when cooling from 1250 so to 960. .176).

Since the-ratio of specific gas volume to specific oil vapor volume is approximately 20, this would mean that by volume one part of oil vapor would be diluted by about 3 5 parts of gas.

Example ZZ.Assume now a charging stock having 3% sulphur by weight, the vapor of which is to be converted at the same temperature oi 960 F. The vapor from this charging stock may be assumed to contain the same percentage of sulphur by weight. If now three parts by weight of gas are used to one part by weight of oil vapor, then the sulphur content of the mixtureir. the reaction chamber will be below 1% or more exactly 825%, assuming the value of the sulphur content of the gas to be .1% by weight, I

gas above 960 must be 17, 1. e. Consequently the hot gas will be supplied at 977 F.

If the oil vapor is heated, say to 725 F. only, then a simple calculation will give the temperature of the gas to be supplied as 985 F. for the same weight ratio.

Other means may be employed for the purpose of regulating the temperature of the vapor fed to the reaction chamber 13, as for example by increasing the pressure in the vapor space of the evaporator 10 which will have the effect of increasing the temperature of the saturated oil vapor produced therein. 'Other features of the process and apparatus shown herein but not claimed are claimed in other pending applications owned by the present assignee.

I claim:

1. In the process of converting oil containing an excess of one per cent of sulphur to produce compounds suitable as motor fuels, in which process a heat carrier gas containing less than the below defined critical value of sulphur is used to bring about the conversion of the oil in the vapor phase, the steps which consist in first vaporizing the oil, then admixing it with said heat carrier gas heated to above the conversion temperature to produce a mixture having a predetermined temperature whereby to effect the conversion of said vapor under predetermined temperature conditions, and so regulating the temperature and relative volumes of the components of said mixture as to bring the per cent of sulphur therein to a value not exceeding a predetermined value below wlich no substantial corrosion takes place whereby an oil ofrelatively high sulphur content undergoes greater dilution with the heat carrier gas than an equivalent oil of lower sulphur content and then subjecting the converted mixture to liquefaction conditions to separate out products suitable as motor fuels.

'2. The process according to claim 1 in which the temperature of the oil vapor is varied in accordance with the amount of sulphur therein.

3. The process according to claim 1 in which a mixture of oil, vapor and gaseous heat-carrier is obtained having a sulphur content not exceeding 1%. v

4. The process according to claim 1v in which the conversion temperature is in excess of 900 F.

5. The process according to claim 1 in which the temperature of the oil vapor is varied in accordance with the amount of sulphur therein by superheating same in such a manner as to avoid cracking of the vapor prior to its admixture with said heat-carrier gas.

6. In the process of converting oil into compounds suitable as motor fuels in which process a heat carrier gas is used to bring about the conversion thereof in the vapor phase, the steps which consist in first determining the per cent of sulphur in the oil to be converted, vaporizing the oil, then admixing it with a heat carrier gas of known sulphur content less than the below defined critical value and heated to above the conversion temperature to bring about the conversion of said oil at a predetermined initial temperature and so regulating the temperature and relative volume of one of the components of said mixture as to bring the percentage of sulphur therein to a predetermined value not exceeding substantially one per cent, .below which no substantial corrosion takes place, whereby an oil of relatively high sulphur content undergoes greater dilution with the heat carrier gas than an e uivalent oil of lower sulphur content, and ten subjecting the converted mixture to liquefaction cqriditions to separate out products suitable as motor fuels.

In testimony whereof I have afiixed my signature to this specification.

ALBERT P. SACHS. 

